<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script src="https://cdn.jsdelivr.net/npm/vue@2"></script>
<div id="vue">
    <span>{{abc}}</span>
</div>
<script>
    new Vue({
        data() {
            return {
                abc: 123
            }
        }
    }).$mount('#vue')
</script>
</body>
</html>